Right Ductus Arteriosus in a Calf

Abstract

Fallot's tetralogy with right ductus arteriosus was detected in a Holstein calf. The right ductus arteriosus measured approximately 6mm in outside diameter. It arose from the pulmonary trunk immediately before the bifurcation into the right and left pulmonary arteries. It ran anteriorly meandering on the right side of the aortic arch and drained into the brachiocephalic trunk immediately before the ramification of the left subclavian artery. The aortic arch was normally formed by the left fourth aortic arch. This ductal anomaly was considered to have developed at the early formative stage of the circulatory system as a rudiment of the distal portion of the right sixth aortic arch.